(a) State one advantage of using jute bags over plastic bags for shopping.
(b) Write a common food chain of a pond ecosystem having four links.

Write the common food chain of a pond ecosystem.

What is a food chain ? Write the common food chain of a pond ecosystem .

What are the advantage of cloth bags over plastic bags during shopping ?

Vinod went to his ancestral village alongwith his father during the summer holydays. He found that women of the village still used dried cow-dung cakes (uple) as the fuel to cook food and for other heating purposes. One day Vinod went to Panchayat meeting in the village which is attended by all the village elders and requested them to instal 'Gobar gas plant' in the village and use cow-dung in it to produce gobar gas, instead of burning cow-dung cakes directly. He explained the advantages of using gobar gas as a fuel instead of cow-dung cakes. Every one liked the idea and thanked Vinod for guidance. (a) State two disadvantages of using dried cow-dung cakes as a fuel for cooking food. (b) State two advantages of using gobar gas as a fuel for cooking food. (c) What values are displayed by Vinod in this whole episode ?

Once there was a heavy downpour for about three hours in the early morning. Irfan and his family were finding it difficult to carry out their morning chores as the sewer water was flowing back into the toilets, the road outside was flooded with water and they could not move out. On this serious problem, Irfan called a meeting of the residents and said that we are using too much polythene bags and other plastic items which we throw here and there, which finally move into the drains and sewer lines which get choked. As these are non-biodegradable, they remain as such for long time. So we should use bags made up of cloth and jute which are biodegradable. Answer the following questions : (i) Name a polymer which is biodegradable. Write the structure of its monomers and the repeating unit. (ii) Write two uses of this polymer. (iii) Write any two values shown by Irfan.